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Full text of "Handbook Of Chemical Engineering - I"

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side by side and connected in parallel, driven by a crankshaft with cranks spaced equally around a circle. They may run at high speeds if direct-connected to a motor or belt driven, but if geared, the speed is generally kept low (see table I). The plungers may be single-acting or double-acting. Triplex power pumps having 3 single-acting plungers give an almost uniform flow of water.
Crank and flywheel pumps are power pumps driven directly from the shaft of a steam engine. The horizontal direct-connected type consists of a regular steam engine with a water end attached to the rear steam-cylinder head. The opposed type has the crankshaft placed between steam end and water end. Any combination of the well-known types of steam or water ends may be used. The piston speed seldom exceeds 300 ft. per minute (see Table I). Vertical crank and flywheel pumps may be cross-compound with two double-acting plungers or triple-expansion with three single-acting plungers. The latter gives much higher economy also a nearly uniform flow of water, and the pump end is simple and accessible.
Express pumps, or high-speed power pumps are built for direct connection to electric motors. A Knowles express pump having two double-acting end-packed plungers, 3J^-in. diameter by 5H-m- stroke, has a capacity of 250 gal. per minute against a head of 1,000 ft. at a speed of 300 r.p.m. Pumps of this type are built in capacities of from 200 to 4,000 gal. per minute against heads from 100 to 2,000 ft. Two duplex express pumps, having two double-acting end-packed plungers, 6*-Hie-in- diameter by 15-in. stroke, were installed for unwatering the Comstock Lode, Virginia City, Nev. The capacity was 1,600 gal. per minute against 1,550 ft. head, speed 195 r.p.m. or a piston speed of 488 ft. per minute. The valves were of the automatic poppet form, 13 in each set, the valve area was 103.35 sq. in. or 294 per cent of the plunger area, giving a water velocity of 165 ft. per minute through the valve scats. Each pump weighed 300,000 Ib. and cost $80,000. The cost including the motors was 13.3 cts. per pound, the cost per gallon of capacity $25, the total installation was estimated at $125,000 or $40 per minute-gallon.1
Deep-well pumps of the bucket type are designed for use on non-flowing wells where the water does not stand within suction distance. Two methods are employed: In the plain tube well (Fig. 6) the well pipe with open ends is sunk to the proper depth where a sufficient water-bearing stratum is penetrated. The strainer A is then lowered to bottom of the well and the well pipe drawn back far enough to expose the slotted portion. The working barrel B is then lowered into the gum packer on top of strainer and tapped firmly into place. The top of the well pipe is provided with a tee for discharge connection. The
1 At pre-war-prices.   EDITOR. 8
FIG. 5.                FIG. 6.
Deep-well pumps.